Power output control



July 4, 1939. H. A CENTERVALL POWER OUTPUT CONTROL iled Jan. 21, 1936 440/1515 osuvmv PUMP INVENTOR.

2;, Jam/1w #0604 awn-Emu.

ATTORNEYS Patented July 4, 1939 PATENT OFFICE POWER OUTPUT ml Hugo A.Centervall, Brooklyn, N. I" auignor to Manly Corporation. New York.

poration of Dehware N- Y l 00131- Application January 21, ms, Serial'N... was

This invention relates to means for controlling the output from a sourcesupplying power for which are'operated intermittently. One important usefor it is in connection with fluid pressure operated devices whenemployed to perform such functions as steering, braking or clutchoperation 10 on a motor vehicle. I have accordingly chosen to illustratethe invention as applied to a motor vehicle provided with hydraulicpowersteering. In order for the driver to retain full control of the vehicleat all times it is obviously necessary that he be able to turn thesteering members any desired amount either as slowly'or as rapidly ashe, may wish. When steering is .done by hy draulic power-means it istherefore necessary for the source of pressure fluidiusually a pump) toat all times deliver such fluid in a quantity suflicient to cause thehydraulic steering appa ratus to move the steering members at whateverrate of speed'the driver may wish to employ. In systems heretoforeproposed a constant displacement pump usually has been operated by thedriving engine of the vehicle but as the speed of the driving engine issubject to wide variation it has been necessary to make the pump of acapacity large enough to deliver the required maximum volume of fluid inthe minimum required timewith the engine running at low'speed. As thespeed of I the engine increases, the volume of fluid delivered by such apump increases proportionatelyso that more fluid is pumped than isneeded. This results in, power losses which become appreciable at thehigher engine speeds and is apt to cause trouble due to heating or tochurning of the fluid.

li a smaller pump is used,'however, the supply of v fluid available atthe lower engine speeds is-insuf 40 flcient to operate the hydraulicpower steering apparatus as rapidly as may be desired.

Under ordinary conditions a motor vehicle,

such as the conventional automobile, is operated for the most'pa'rtwhile traveling in a substarr-v tially straight path and its operationat relatively high speeds is confined largely thereto. There is littleor no occasion for any material movement of the steering control membersunder these circumstances and hence only a small quantity of pressurefluid is required for operation of the hydraulic power steering device.It will be obvious, however; that a constant capacity pump driven 1 I bythe motor yehiclesxenginewould frequently in operating at itsJlighestunder these conditions and hence would be delivering the maximumquantity of fluid at a time when it is not Bimilarlmsharp turns of thevehicle are usually made at relativelylow speeds and hence the constantdisplacement pump would de- 5 liver a relatively small volume of fluidat a. time when a maximum amount of pressure fluid is required for theoperation of the power steering ap- Anobiect of this invention is toprovide sim- 10 pie and elective means whereby the source of powerdelivers a minimum quantity under normal conditions of operation butmakes available the needed increased amount of power whenever the powerapparatus is operated beyondits normal limits of use. A more specificobject is to provide a practical mechanism or this class for fluid powersystems. Other objects will appear from the'following description of anillustrative embodiment of the present invention.

In the accompanying drawing: I

Fig. 1 is a side elevation of a motor vehicle embodying a preferred formof the present invention .shown in schematic arrangement and showingtheposition ofthe parts when the vehicle is traveling 'in a substantiallystraight path.

Fig. 2 is similar to Fig. 1 and shows the position of'the parts when thevehicle is making the sharpest possible turn toward the left.

Referring nowto Fig. 1 of the drawing, the vehicle is driven by theusual internal combustion engine II which is supported in any preferredmanner upon the frame of the vehicle, a portion of one side member ll ofwhich is shown. The engine comprises the usual cylinder block i2 andcrankcase I3 and is operatively connected with the rear road wheels, notshown, by means of the usual transmission mechanism, not shown. The 7speed of the engine may be controlled in any suitable manner. 3 linefluid circuit includes a pump ll whose driving shalt, not shown, isoperatively connected with the engine ll in any preferred manner. Theinlet or suction port of the pump is is connected, as by,a .pipe I.witha supply of fluid in the crank case it and the appropriate highpressure or discharge pipe It leads from the discharge port of the pumpI4 and terminates in the con-- trol valve .mechanism of the hydraulicpower steering apparatus. The fluid circuit further includes a suitablereturn'or discharge pipe l1 leadingfrom-the hydraulic control mechanismto the interior of the crank case It. Appropriate safety and exhaustvalves, not shown, are also provided by which the maximum pressure ofthe fluid is so limited and excess fluid not needed for the operation ofthedriven device is returned to the reservoirinthecrankcasellinthecustomary manner. i

The pump it may be of any preferred type whose discharge or capacity perrevolution may be varied, as for example, the variable capacity strokeof said pistons and hence the capacity'of the pump may be varied frommaximum to zero by sliding said crankmechanism transverse the axis ofrotation. With the parts in the position shown in Fig. 1, the crankmechanism, which is attached to the inner end of the control rod II, isin its extreme inward position and if desired the arrangement may bemade'such that. the crank mechanism is concentric with the center ofrotation. In this position of the crank mechanism, the pump delivers theminimum amount or fluid per revolution, which may be made zero or anydesired amount. Outward movement of the crank echanism by means ofsimilar-movement of -t control rod ll causes a corresponding increase-inthe length of the stroke of the pump pistons and hence in the deliveryper revolution of the pump until the'crank mechanism reaches its maximumoutward or eccentric position as is the case when the parts are in theposition shown in Fig; 2. y

The steering mechanism includes the usual 1-0-- tatable steering wheel2| mounted upon one end of the steering shaft 2| whose lower endisappropriatel'y connected-with the usual worm 22 for simultaneousrotation therewith. The worm I! engages-the usual sector I! which isguided upon one end of the usual rotatably mounted cross shaft M towhose other end is fastened the upper endof'the pitman arm 2'. Thearrangement is such that manual rotation of thesteeringwheelllcausesthepitmanarmlltoswingwhose outer end is'pivotallyconnected as at 32 to the depending bracket II which is suita ynipported upon the side frame member ii. The hydraulic power apparatusalso includes a movablecylinder bodv ll formed withthe usual mammecylinder a in which thepiston a is slidabb fitted. The ends of thecylinder "are suitably connected with the control mechanism so' thatwhen one end of said cylinder is connected with the'prcss'ure fluid.inlet pipe "the other end'of said cylinder isconnected with the returnpipe i1v which leads back to the interior ofthecrankcaseli Themeclnnism, not shown, for controlling the operation of the hydraulicpower cylinder is body and is adapted tOQbe'actuated bythe lower end ,ofthe pitman' arm 25. The arrangement is such that when the steering wheel2| isturned in a counter-clockwise direction the pitman arm 25 swingsforwardly or toward the left, as viewed in Figs. 1 and 2, and pressurefluid is admitted to the left end of the cylinder 36 which causes thecylinder body 35 and its attached parts to be moved forwardly or towardthe'left. Similarly, as the steering wheel is turned in a clockwisedirection pressure fluid is admitted to the rear or right end of thecylinder 36, as viewed in Figs. 1 and 2, and the cylinder body 35 andits con-' nected parts are moved rearwardly or toward the right. i

The movable cylinder body is adapted to be operatively connected withthe steered road wheels of the vehicle in order that steering maybeeflected by power and said cylinder body 35 is attached by the usualball and socket construction to one endof the usual drag link 26 hereshown as broken ofl. The'drag link 26 is pre sumed to be operativelyconnected with a contional front road wheel assembly of an automobile inthe usual manner, so that forward movement of said drag link26 away fromits neutral or straight-ahead position, as shown in vcapacity of saidpump. In the present instance the movable cylinder body 35 is pivotallyconnected to one end of ashort link ll whose other end is pivotallyconnected with the adjacent end of the camrod Is. The cam 'rod 43 isadapted to be freely movable lengthwise but is held against substantialmovement in any other direction as by the appropriate supporting means44 carried by the side frame member ii and the supporting means II, hereshown carried by the crank case It. The arrangement is such that the camrod 4! ismoved lengthwise whenever there is corresponding movement ofthe cylinder body II, the pivotal connection of the link 40 permittingsaid link to adjust itself as required by the varying angularity of saidcylinder body "with respect to said cam rod 43 in the various positionsof adjustment of the steering mechanism. The cam rod 43 is provided withfan appropriate cam l which is adapted to cooperate with a roller or camfollower ll securely attached to the outer end of the control rod it.

means of a spring, acting against the shoulder ll formed on the controlrod it. The arrangement is such that the spring ll forces the controlrod ll,'and hencenthe attached crank mechanism of thecam rod 43 whichcompresses the spring 48 and forces the control rod 'il outwardly.

It will be evident that the cam 46' determines the position of theroller I! and the control 'rod ll and hence of the crank mechanismof thepump. ll. The cam I! may obviously be of any suitably located within themovable cylinder- SI: it is-ofthe well-known follow-up type soQthat thestroke of the pump 'll' maybe varied between any desired 55. The roller1 is held against the cam 46' by minimum and maximum lengths and so thatthe varl'ation of the length of the pump stroke may be made to occur atrate. In the a substantially straight central portion A-B, as

the parts are substantially in the position shown indicated in Fig. 2.It will be obvious that there will be no change in the length of thepump stroke as long as the roller 41 is in contact therewith. IAdjoining the central portion A--B on each of its sides, the cam 46 isformed with curved portions adapted to progressively increasethe outwardmovement of the roller 41 as the cam rod 43 is moved out of its centralposition as shown in Fig. 1, and hence to progressively increase thestroke of the pump I4'until the stroke of said p'ump I4 has been broughtto its maximum.

When the vehicle is moving in a straight path in Fig. 1 and the variablecapacity pump I4 delivers its minimum volume .of fluid per revolu- 41'when the steering members. arev moved throughout the limited range ofsteering required tion. Relatively little movement of thesteeringmembers is ordinarily required when the vehicle is traveling on asubstantially straight roadway but it is frequently necessary to turnthe steering members within a limited range in one direction or theother in order to make adjustments necessitated by irregularities in thesurface of the roadway, etc.. This condition obtains for the greatmajority of time which the vehicle is operated and particularly when itis moving at rela-' tively high speeds. Very little steering of the.

under'this condition of travel. The minimum length of the strokeof thepump I4 as thus determined is made such as to supplyadequate pressurefluid for the operation of the power steering mechanism throughout thisrange thus assuring an ample supply of pressure fluid but .without anymaterial excess.

the movable cylinder body 35 and its attached When the driver'wishes tosteer toward the left he turns the steering wheel 20 in acounterclockwise direction' and the pitman arm 25 swings forwardly ortoward the left, as viewed in Figs. 1 and 2. Pressure fluid is thenadmitted to the forward or'left end of the cylinder "and parts are movedforwardly, causing the steered the left, as viewed in Fig. 1. againstthe roller 41 forcesoutwardly the conroad wheels to move in a directionwhich turns the vehicle toward the left. As the cylinder. body 35 movesforward, it actuates the cam rod 43 which is likewise moved forwardly ortoward trol rod I8 and the connected crank mechanism of the variablecapacity pump I4 and thevvolume of fluid delivered by the pump I4 isthus instantaneously increased and made available for .movement of themovable cylinder body 35. It

will be observed that in the'present embodiment the strokeof the pump I4is brought to its maximum length when the steering mechanism has moveda; comparatively shortdistance beyond its 1 range of normal operationfor. straight-ahead travel. Fig. 2 shows the position of the parts whenthe steered road wheels are in such position as to cause the vehicle tomake its sharpest possible turn toward the left and it will be observedthat the capacity of the pump I4 is maximum. When the steering controlsare brought back to their normal-,or straight-aheadposition,

' turned away from The substantially straight central The cam 48 actingas shown in Fig. 1, the cam rod 43 is likewise returned to its normal orcentral position and the stroke of the pump is thus reduced.

obviously reversed. It will be observed however that the stroke of thepump I4 is increased in the same manner and in substantially the sameamount as for a corresponding turn toward the left. Variations in thisarrangement may obviously be made. as conditions require. For example,the

cam may be made such that the stroke of the,

pump I4 is atits minimum length when the roller 41 is in contact with asingle point of the cam 46, and similarly, the changing of the stroke ofthe pump from minimum to maximumlength may be made to take place almostinstantaneously' upon relatively small lengthwise movement of the camrod 43.

It will be observed that movement of the cam rod 43 and hence themovement of the. control .mechanism'of the pump I4 is eifected by power25 from the hydraulic power apparatus. It will further be evident thatthedevice operates to provide a minimum quantity of pressure fluid underconditions when minimum pressure fluid is required but makes availablepressure fluid in the needed quantity when steering controls are theirnormal or straight-ahead,

position.'

It is to be understood that the above is merely an exemplifyingdisclosure and that changes may be made in the apparatus withoutdeparting from the applicants invention which is defined in the appendedclaims. J

I claim:

1. In a fluid pressure operated device, a variable stroke pump, a powermechanism operated by fluid delivered by said pump, man'ually operatedcontrol means for said .power mechanism,

and separate stroke-varying means for said pump acting independently ofthe operation of .'the manually operated control means to determine thevolume of fluid delivered bythe'pump at the diiferent points of range ofmovement of the power mechanism, said stroke-varying means being adaptedto effect pump stroke of minimum length upon movement of said powermechanism responsive to movement of said manually operated control meansthroughout a limited range and to increase said pump stroke uponmovement of said power mechanism responsive to movement of said manuallyoperated control means;

beyond said limited range.

2. In a power steering device, manually movable control means for saiddevice, fluid power means operatively responsive to movement of saidcontrol means, steering. means operatively 'conthe volume of fluiddelivered by the variablecapacity pump at the different points of rangeof movement of the steering means, and to produce a minimum capacity perrevolution of said pump upon movement of said steering device through-vout a limited range and to increase the capacity of said pump perrevolution upon movement of nected with said fluid power means, avariable said steering device beyond said limited range. 3. Incombination, a variable delivery pump, driven means actuated by fluiddelivered by said pump, control means for connecting said pump with saiddriven means and a separate power output control means for said pumpcoordinated with said driven means to alter the volume or fluiddelivered by said pump simultaneously with. the

operation of said driven means, said power output control means actingindependently of the operation ol said first named control means todetermine the volume'of fluid delivered by the pump at the differentpoints or range of movement or the driven means.

4. In combination, a pump of variable capacity per revolution, a deviceactuated by fluid delivered by said pump, means Ior connecting anddisconnecting said pump with said device to regulate the operationthereof, and a capacity control mechanism for determining the volume offluid delivered by said pump, said capacity control mechanism beingoperated in unison with and solely in response to movement of saiddriven device to vary and determine the volume of fluid said drivenmeans and conformably with the position- 01' said driven means inmovement.

6. In combination, a power source of variable output, driven meansactuated by power delivered by said source, follow-up controlmeans'regits range or ulating the operation of said driven means, saidfollow-up control means including a manually movable member and beingactuated by relative 'movement between said manually movable member andsaid driven means, and power output control means for said power sourcecoordinated with said driven means and actuated solely in response tomovement thereof. to alter the power output from said source, saidmanually movable member acting solely through said follow-up consourcecoordinated with said driven means and actuated solely in response tomovement thereot to alter the power output from said source con- 8. Incombination, a power source of variable output, driven means actuated bypower delivered by said source, control means for connecting anddisconnecting said power source with said .driven 'means to regulate theoperation thereof, and

separate power output control means for said power source coordinatedwith said driven means, said power output control means actingindependently of said first named control means to cause a predeterminedvariation in the rela ve 'output of power from said source contormablywith the difl'erent points in the range ment of the driven means.

9. In combination, a fluid power source of variable output, driven meansactuated by fluid power delivered by said source, control valvemechanism for regulating the operation of said driven means, andseparate fluid power output control means for said power source, saidfluid power output control means acting independently of the operationof said flrst named control means and being responsive solely to theoperation of said driven means to regulate the relative fluid poweroutput from said source at different points in the range of movement ofsaid driven means.

10. In combination,.a variable delivery pump, a device actuated by fluiddelivered by said pump, means for connecting and disconnecting ofmovesaid pump with said device and a power output mine the relativevolume of fluid delivered by the iormably' with the diflerent positionsof said driven means in its range of movement.

ment of the driven device.

HUGO A. CENTER-TAIL

